With the wound that the deer had, he obviously was dying of starvation.
His system used up any fat reserves that would keep him alive as long as possible, which naturally changed the look, feel, texture and taste of the meat.
This would compare to eating a cow that was on a drought stricken range compared to one that was fattened up in a feed lot. About the only thing that such a cow would be good for, would be grinding. I think that that would be your best option and be sure to add lean pork and some beef.
There is no way to change the quality to match a healthy well fed animal.
Dave